An electronic tuning circuit of the prior art as disclosed in Japanese Patent Application 50-151489 (laid open to public inspection on July 23, 1977 as Publication No. 52-75153) includes an image trapping circuit which partially extends parallel with a pair of resonating transmission lines and partially extends at right angles crossing one of the transmission lines and coupled with a coupling element associated with the transmission line with which the trapping circuit crosses. The disclosed image trap provides an improvement of image interference ratio at a particular image frequency, but exhibits unsatisfactory value of ratio at other frequencies.